Multifunctional Redox Polymers: Electrochrome,Polyelectrolyte, Sensor,Electrode Modifier,Nanoparticle Stabilizer,and Catalyst Template

Simple “click” polycondensation metallopolymers of redox‐robust bis(ethynyl)biferrocene (biFc) and di(azido) poly(ethylene glycol) (PEG400 and PEG1000) were designed for multiple functions including improvement of water solubility and biocompatibility, the introduction of mixed valency and sensing capabilities, and as nanoparticle stabilizers for catalysis.     

Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity,Stability, and Temperature‐ Dependent Activation Properties

Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs₄[α‐SiW₁₂O₄₀]⋅n H₂O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was −67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Au^δ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions.     

Photocatalysis with Quantum Dots and Visible Light: Selective and Efficient Oxidation of Alcohols to Carbonyl Compounds through a Radical Relay Process in Water

Selective oxidation of alcohols to aldehydes/ketones has been achieved with the help of 3‐mercaptopropionic acid (MPA)‐capped CdSe quantum dot (MPA‐CdSe QD) and visible light. Visible‐light‐prompted electron‐transfer reaction initiates the oxidation. The thiyl radical generated from the thiolate anion adsorbed on a CdSe QD plays a key role by abstracting the hydrogen atom from the C−H bond of the alcohol (R¹CH(OH)R²). The reaction shows high efficiency, good functional group tolerance, and high site‐selectivity in polyhydroxy compounds. The generality and selectivity reported here offer a new opportunity for further applications of QDs in organic transformations.     

Sulfur‐33 Isotope Tracing of the Hydrodesulfurization Process: Insights into the Reaction Mechanism,Catalyst Characterization and Improvement

The novel approach based on ³³S isotope tracing is proposed for the elucidation of hydrodesulfurization (HDS) mechanisms and characterization of molybdenum sulfide catalysts. The technique involves sulfidation of the catalyst with ³³S‐isotope‐labeled dihydrogen sulfide, followed by monitoring the fate of the ³³S isotope in the course of the hydrodesulfurization reaction by online mass spectrometry and characterization of the catalyst after the reaction by temperature‐programmed oxidation with mass spectrometry (TPO‐MS). The results point to different pathways of thiophene transformation over Co or Ni‐promoted and unpromoted molybdenum sulfide catalysts, provide information on the role of promoter and give a key for the design of new efficient HDS catalysts.     

Effective and Selective Catalysts for Cinnamaldehyde Hydrogenation: Hydrophobic Hybrids of Metal–Organic Frameworks,Metal Nanoparticles,and Micro‐ and Mesoporous Polymers

Metal–organic frameworks (MOFs) as selectivity regulators for catalytic reactions have attracted much attention, especially MOFs and metal nanoparticle (NP) shelled structures, e.g., MOFs@NPs@MOFs. Nevertheless, making hydrophilic MOF shells for gathering hydrophobic reactants is challenging. Described here is a new and viable approach employing conjugated micro‐ and mesoporous polymers with iron(III) porphyrin (FeP‐CMPs) as a new shell to fabricate MIL‐101@Pt@FeP‐CMP. It is not only hydrophobic and porous for enriching reactants, but also possesses iron sites to activate C=O bonds, thereby regulating the selectivity for cinnamyl alcohol in the hydrogenation of cinnamaldehyde. Interestingly, MIL‐101@Pt@FeP‐CMP^sponge can achieve a high turnover frequency ( 1516.1 h⁻¹), with 97.3 % selectivity for cinnamyl alcohol at 97.6 % conversion.     

CO2 Hydrogenation on Cu/Al2O3: Role of the Metal/Support Interface in Driving Activity and Selectivity of a Bifunctional Catalyst

Selective hydrogenation of CO₂ into methanol is a key sustainable technology, where Cu/Al₂O₃ prepared by surface organometallic chemistry displays high activity towards CO₂ hydrogenation compared to Cu/SiO₂, yielding CH₃OH, dimethyl ether (DME), and CO. CH₃OH formation rate increases due to the metal–oxide interface and involves formate intermediates according to advanced spectroscopy and DFT calculations. Al₂O₃ promotes the subsequent conversion of CH₃OH to DME, showing bifunctional catalysis, but also increases the rate of CO formation. The latter takes place 1) directly by activation of CO₂ at the metal–oxide interface, and 2) indirectly by the conversion of formate surface species and CH₃OH to methyl formate, which is further decomposed into CH₃OH and CO. This study shows how Al₂O₃, a Lewis acidic and non‐reducible support, can promote CO₂ hydrogenation by enabling multiple competitive reaction pathways on the oxide and metal–oxide interface.